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On Types of Isolated KKT Points in Polynomial Optimization

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Journal of Systems Science & Complexity 2023年第5期36卷 2186-2213页

作者： GUO Feng JIAO Liguo KIM Do Sang pham Tien-Son School of Mathematical Sciences Dalian University of TechnologyDalian 116024China Academy for Advanced Interdisciplinary Studies Northeast Normal UniversityChangchun 130024China Department of Applied Mathematics Pukyong National UniversityBusan 48513South Korea Department of Mathematics Dalat UniversityDalat 96300Vietnam.

Let f be a real polynomial function with n variables and S be a basic closed semialgebraic set in R^(n).In this paper,the authors are interested in the problem of identifying the type(local minimizer,maximizer or not extremum point)of a given isolated KKT point x^(*)of f over *** this end,the authors investigate some properties of the tangency variety of f on S at x^(*),by which the authors introduce the definition of faithful radius of f over S at x^(*).Then,the authors show that the type of x^(*)can be determined by the global extrema of f over the intersection of S and the Euclidean ball centered at x^(*)with a faithful ***,the authors propose an algorithm involving algebraic computations to compute a faithful radius of x*and determine its type.

关键词： Faithful radii KKT points polynomial functions tangency varieties types

Rapid design of top-performing metal-organic frameworks with qualitative representations of building blocks

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npj Computational Materials 2023年第1期9卷 585-598页

作者： Yigitcan Comlek Thang Duc pham Randall Q.Snurr Wei Chen Department of Mechanical Engineering Northwestern UniversityEvanstonILUSA Department of Chemical and Biological Engineering Northwestern UniversityEvanstonILUSA

Data-driven materials design often encounters challenges where systems possess qualitative(categorical)***,representing Metal-organic frameworks(MOFs)through different building blocks poses a challenge for designers to incorporate qualitative information into design optimization,and leads to a combinatorial challenge,with large number of MOFs that could be *** this work,we integrated Latent Variable Gaussian Process(LVGP)and Multi-Objective Batch-Bayesian Optimization(MOBBO)to identify top-performing MOFs adaptively,autonomously,and *** showcased that our method(i)requires no specific physical descriptors and only uses building blocks that construct the MOFs for global optimization through qualitative representations,(ii)is application and property independent,and(iii)provides an interpretable model of building blocks with physical *** searching only~1%of the design space,LVGP-MOBBO identified all MOFs on the Pareto front and 97%of the 50 top-performing designs for the CO_(2) working capacity and CO_(2)/n2 selectivity properties.

关键词： properties qualitative autonomous

EXISTEnCE AnD STABILITY OF PERIODIC AnD ALMOST PERIODIC SOLUTIOnS TO THE BOUSSInESQ SYSTEM In UnBOUnDED DOMAInS

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Acta Mathematica Scientia 2022年第5期42卷 1875-1901页

作者： Thieu Huy nGUYEn Truong Xuan pham Thi ngoc Ha VU The Sac LE School of Applied Mathematics and Informatics Hanoi University of Science and Technology Vien Toan ung dung va Tin hocDai hoc Bach khoa Hanoi 1DaiCoVietHanoiVietnam Department of Mathematics Faculty of Information TechnologyThuyloi university Khoa Cong nghe Thong tinBo mon ToanDai hoc Thuy loi175 Tay SonDong DaHa NoiViet Nam Thuyloi University Dai hoc Thuy Loi175 Tay SonDong DaHanoiViet Nam

In this paper we investigate the existence and stability of periodic solutions(on a half-line R_(+))and almost periodic solutions on the whole line time-axis R to the Boussinesq system on several classes of unbounded domains of R^(n) in the framework of interpolation *** the linear Boussinesq system we combine the L^(p)—L^(q)-smoothing estimates and interpolation functors to prove the existence of bounded mild ***,we prove the existence of periodic solutions by invoking Massera’s *** also prove the existence of almost periodic *** we use the results of the linear Boussinesq system to establish the existence,uniqueness and stability of the small periodic and almost periodic solutions to the Boussinesq system using fixed point arguments and interpolation *** results cover and extend the previous ones obtained in[13,34,38].

关键词： Boussinesq systems periodic solutions almost periodic solutions unbounded domains smoothing estimates dual estimates interpolation spaces stability

Defect engineering of water-dispersible g-C_(3)n_(4) photocatalysts by chemical oxidative etching of bulk g-C_(3)n_(4) prepared in different calcination atmospheres

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Journal of Materials Science & Technology 2022年第8期103卷 232-243页

作者： Thi Kim Anh nguyen Thanh-Truc pham Bolormaa Gendensuren Eun-Suok Oh Eun Woo Shin School of Chemical Engineering University of UlsanDaehakro 93Ulsan 44610South Korea Department of Material Technology Faculty of Applied ScienceHo Chi Minh City University of Technology and Education(HCMUTE)No.1 Vo Van Ngan StreetLinh Chieu WardThu Duc DistrictHo Chi Minh City 700000Viet Nam

In this study,water-dispersible graphitic carbon nitride(g-C_(3)n_(4))photocatalysts were successively prepared through the chemically oxidative etching of bulk g-C_(3)n_(4) that was polymerized thermally in different calcination atmospheres such as air,CO_(2),and n_(2).The different calcination atmospheres directly influenced the physicochemical and optical properties of both bulk and water-dispersible g-C_(3)n_(4),changing the photocatalytic degradation behavior of methylene blue(MB)and tetracycline hydrochloride(TCHCl)for water-dispersible g-C_(3)n_(4).The bubble-burst process in the thermal polymerization of thiourea produced defective edges containing C=O groups that preferred substituting the C-nHx groups over bulk g-C_(3)n_(4).In the oxygen-free n_(2) atmosphere among the different calcination atmospheres,more C=O functional groups were generated on the defective edges of bulk g-C_(3)n_(4),resulting in the highest n vacancy of the tri-s-triazine *** the successive chemical oxidation,S-or O-containing functional groups were introduced onto water-dispersible g-C_(3)n_(4).The water-dispersible g-C_(3)n_(4) photocatalyst from the oxygen-free n_(2) atmosphere(nTw)contained the most O-and S-functional groups on the g-C_(3)n_(4) ***,nTw exhibited the highest photocatalytic activity in the MB and TC-HCl photodegradation because of its slowest recombination process,which was ascribed to the unique surface properties of nTw such as abundant functional groups on the defective edges and n-deficient property.

关键词： g-C_(3)n_(4) Water-dispersible photocatalyst Calcination atmosphere Charge separation Chemically oxidative etching Defect edges

Combining SnO_(2-x)and g-C_(3)n_(4)nanosheets toward S-scheme heterojunction for high selectivity into green products of nO degradation reaction under visible light

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Journal of Materiomics 2022年第1期8卷 1-8页

作者： pham Van Viet Thanh-Dat nguyen Dai-Phat Bui Cao Minh Thi Faculty of Materials Science and Technology University of ScienceVNU-HCM227 Nguyen Van Cu StreetDistrict 5Ho Chi Minh City700000Viet Nam Vietnam national University-Ho Chi Minh City Thu Duc DistrictHo Chi Minh City700000Viet Nam Ho Chi Minh City University of Technology(HUTECH) 475A Dien Bien Phu StreetBinh Thanh DistrictHo Chi Minh City700000Viet Nam

nOx emissions cause many negative impacts on the living *** photocatalysis of semiconductors is superior for nitric oxide(nO)degradation due to their low redox *** this report,we combine SnO_(2-x)/g-C_(3)n_(4)heterojunction photocatalyst toward the high selectivity into green products under visible light *** show that SnO_(2-x)/g-C_(3)n_(4)heterojunction degraded 40.8%of nO,which is 1.6 times higher than that of g-C_(3)n_(4).In addition,the selectivity coefficient of SnO_(2-x)/g-C_(3)n_(4)is higher 3 times than both pure SnO_(2-x)and g-C_(3)n_(4).Furthermore,SnO_(2-x)/g-C_(3)n_(4)expresses a superior stability for nO photocatalytic-degradation after five *** scavenger trapping test results,and electron spin resonance(ESR)analysis also provide more understanding of the charge transfer mechanism of ***_(2-x)/g-C_(3)n_(4)heterojunction shows a high removal efficiency of nO gas,making it an up-and-coming environmental treatment candidate.

关键词： G-C_(3)n_(4) nO removal Oxygen vacancies Photocatalysis S-scheme

Mechanistic aspects of facet-dependent CH_(4)/C_(2+)selectivity over aχ-Fe_(5)C_(2)Fischer-Tropsch catalyst

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Green Energy & Environment 2022年第3期7卷 449-456页

作者： Thanh Hai pham Junbo Cao nan Song Yueqiang Cao Bingxu Chen Gang Qian Xinggui Zhou De Chen Xuezhi Duan State Key Laboratory of Chemical Engineering East China University of Science and Technology130 Meilong RoadShanghai200237China Vietnam Institute for Tropical Technology and Environmental Protection 57A Truong Quoc DungHo Chi MinhViet Nam Department of Chemical Engineering Norwegian University of Science and TechnologyN-7491TrondheimNorway

Structure-performance relationship is a complex issue in iron-catalyzed Fischer-Tropsch synthesis,and it is not easy to elucidate it by experimental ***-principle calculation is a powerful method for explaining experimental results and guiding catalyst *** this study,we investigated the reaction mechanisms of CH_(4)formation and C-C coupling on fourχ-Fe_(5)C_(2)surfaces and established the kinetic equations to compare the rates of CH_(4)formation and C_(1)+C_(1)coupling reactions and determine the CH_(4)/C_(2+)*** results show that the geometry of theχ-Fe_(5)C_(2)surfaces has little effect on the formation rate of CH_(4);however,the C_(1)+C_(1)coupling reactions are significantly affected by the surface *** C_(1)+C_(1)coupling reaction rates on the terraced-like(510)and(021)surfaces are much higher than those on the stepped-like(001)and(100)*** on these results,we established a Brùnsted-Evans-Polanyi(BEP)relationship between the effective barrier difference for CH_(4)formation and C_(1)+C_(1)coupling(ΔE_(eff))and the adsorption energy of C+4H(ΔE_(C+4H))onχ-Fe_(5)C_(2)surfaces.ΔE_(C+4H)can be used as a descriptor for CH_(4)/C_(2+)selectivity on different surfaces ofχ-Fe_(5)C_(2).

关键词： selectivity catalyst coupling

nitroxy-and azidomethyl azofurazans as advanced energetic materials

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Defence Technology（防务技术） 2022年第8期18卷 1369-1381页

作者： Aleksei B.Sheremetev Svetlana F.Mel'nikova Elizaveta S.Kokareva Ruslan E.nekrutenko Kirill V.Strizhenko Kyrill Yu Suponitsky Thanh Dat pham Alla n.Pivkina Valery P.Sinditskii Zelinsky Institute of Organic Chemistry Russian Academy of Sciences47 Leninsky ProspMoscow119991Russia Saint Petersburg State Institute of Technology 26 Moskovskii PrSt Petersburg190013Russia Mendeleev University of Chemical Technology Moscow125047Russia n.n.Semenov Federal Research Center for Chemical Physics Russian Academy of Sciences4 Kosygina Str119991MoscowRussia

Progress in the rocket industry is only possible on the basis of new, higher performance and more environmentally friendly materials compared to up-to-date propellant ingredients for liquid, solid, gelled and hybrid propellant systems. In this work, synthetic methods have been developed for the preparation of new energetic azofurazans bearing nitroxymethyl or azidomethyl groups. All prepared compounds were fully characterized by multinuclear nMR and IR spectroscopies, as well as elemental analyses. An analysis of the structural features based on the X-ray single-crystal diffraction made it possible to discuss their influence on the densities of the azofurazans of this study. Thermal decomposition and combustion of nitroxymethyl and azidomethyl azofurazans were studied using a number of complementary experimental techniques, namely thermogravimetry, differential scanning calorimetry, manometry, microthermocouple measurements in the combustion wave. The structural and physical characteristics of these new energetic analogues illustrate the extent to which the nature of the explosophoric groups can be used to tune the performace of the azofurazan framework. These azofurazans possess positive calculated enthalpy of formation and are promising candidates for new environmentally friendly energetic materials.

关键词： Azofurazan Azide nitrate ester X-ray Combustion

Examination of n-T_(9) conditions required by n=50,82,126 waiting points in r-process

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Communications in Theoretical Physics 2021年第10期73卷 147-157页

作者： nguyen Duy Ly nguyen ngoc Duy nguyen Kim Uyen Vinh n T pham Faculty of Fundamental Sciences Vanlang UniversityHo Chi Minh City 700000Vietnam Department of Physics Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Physics Ho Chi Minh City University of EducationHo Chi Minh City 700000Vietnam

We examined the conditions of neutron density(n) and temperature(T9) required for the n = 50, 82,and 126 isotopes to be waiting points(WP) in the r-process. The nuclear mass based on experimental data presented in the AME2020 database(AME and AME ± Δ) and that predicted using FRDM,WS4, DZ10, and KTUY models were employed in our estimations. We found that the conditions required by the n = 50 WP significantly overlap with those required by the n = 82 ones, except for the WS4 model. In addition, the upper(or lower) bounds of the n-T9 conditions based on the models are different from each other due to the deviations in the two-neutron separation *** standard deviations in the nuclear mass of 108 isotopes in the three n = 50, 82, and 126 groups are about rms = 0.192 and 0.434 Me V for the pairs of KTUY-AME and WS4-KTUY models,respectively. We found that these mass uncertainties result in a large discrepancy in the nn-T_(9) conditions, leading to significant differences in the conditions for simultaneously appearing all the three peaks in the r-process abundance. The newly updated FRDM and WS4 calculations can give the overall conditions for the appearance of all the peaks but vice versa for their old versions in a previous study. The change in the final r-process isotopic abundance due to the mass uncertainty is from a few factors to three orders of magnitude. Therefore, accurate nuclear masses of the r-process key nuclei, especially for 76 Fe,81Cu,127Rh,132Cd,192Dy, and 197Tm, are highly recommended to be measured in radioactive-ion beam facilities for a better understanding of the r-process evolution.

关键词： neutron capture r-process nuclear mass isotopic abundance precise mass measurement

Improving Energy and Power Efficiency Using nComputing and Approaches for Predicting Reliability of Complex Computing Systems

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International Journal of Automation and computing 2010年第2期7卷 153-159页

作者： Hoang pham Hoang pham Jr. Department of Industrial and Systems Engineering Rutgers University Timothy Christian School

Opting to follow the computing-design philosophy that the best way to reduce power consumption and increase energy efficiency is to reduce waste, we propose an architecture with a very simple ready-implementation by using an nComputing device that can allow multi-users but only one computer is needed. This intuitively can save energy, space as well as cost. In this paper, we propose a simple and realistic nComputing architecture to study the energy and power-efficient consumption of desktop computer systems by using the nComputing device. We also propose new approaches to estimate the reliability of k-out-of-n systems based on the delta method. The k-out-of-n system consisting of n subsystems works if and only if at least k-of-the-n subsystems work. More specificly, we develop approaches to obtain the reliability estimation for the k-out-of-n systems which is composed of n independent and identically distributed subsystems where each subsystem （or energy-efficient usage application） can be assumed to follow a two-parameter exponential lifetime distribution function. The detailed derivations of reliability estimation of k-out-of-n systems based on the biased-corrected estimator, known as delta method, the uniformly minimum variance unbiased estimate （UMVUE） and maximum likelihood estimate （MLE） are discussed. An energy-management nComputing application is discussed to illustrate the reliability results in terms of the energy consumption usages of a computer system with qua（t-core, 8 GB of RAM, and a GeForce 9800GX-2 graphics card to perform various complex applications. The estimated reliability values of systems based on the UMVUE and the delta method differ only slightly. Often the UMVUE of reliability for a complex system is a lot more difficult to obtain, if not impossible. The delta method seems to be a simple and better approach to obtain the reliability estimation of complex systems. The results of this study also show that, in practice, the nComputing archite

关键词： Energy efficiency ncomputing k-out-of-n system exponential distribution reliability estimation uniformly minimum variance unbiased estimate (UMVUE) maximum likelihood estimate (MLE).